Compression bonding device

ABSTRACT

A compression bonding device has a dam member so that when a pressing head is pressed against an object to be pressed, the bonding part is surrounded by the dam member. Thus, even if the surface of the bonding part bulges by pressing, the bulging part is stopped by the dam member and the surface of the bonding part does not horizontally extend. As a result of the absence of horizontal extension of the bonding part, electric components of the object to be pressed are not subjected to a force that horizontally moves the electric components and the electric components are vertically pressed downward and connected to the terminals of the substrate. Thus, an electric device having high connection reliability is obtained.

This is a Continuation of application Ser. No. 12/216,873 filed Jul. 11,2008, which in turn is a Continuation of International Application No.PCT/JP2007/050307 filed Jan. 12, 2007, which claims the benefit ofJapanese Patent Application No. 2006-006517, filed Jan. 13, 2006. Thedisclosures of the prior applications are hereby incorporated byreference herein in their entireties.

BACKGROUND

The present invention generally relates to a compression bonding devicefor packaging electric components on a substrate and packaging processestherefor.

Conventionally, packaging processes for connecting electric componentssuch as semiconductor elements to a substrate have used a compressionbonding device by which the electric components are pressed against thesubstrate with a pressing head under heat.

Reference numeral 101 in FIG. 18( a) represents a conventionalcompression bonding device. The compression bonding device 101 has apedestal 126 and a pressing head 120.

The pressing head 120 has a pressing rubber fitted into a metal frame,or a pressing rubber bonded to a metal plate with an adhesive or aliquid rubber cast into a metal frame and cured within the metal frame,etc.

In the case of a pressing rubber 122 fitted into a head body 121 madefrom a metal frame, the surface of the pressing rubber 122 is flush withthe surface of the head body 121 or projects below the surface of thehead body 121. When the pressing head 120 is pressed against an objectto be pressed 110 on the pedestal 126, the surface of the pressingrubber 122 comes into contact with the object to be pressed 110.

The object to be pressed 110 has a substrate 111 and electric components116, 118 having different thicknesses placed on the substrate 111 sothat steps are formed on the substrate 111 due to the thicknessdifferences between the electric components 116 and 118.

The pressing rubber 122 is formed of an elastic material that deformsunder pressure. The pressing rubber 122 first comes into contact withthe thickest electric component 116. Then, the pressing rubber 122deforms and successively comes into contact with the electric components116, 118 in the order of thickness from the thickest electric component116 to thinnest electric component 118. Finally, all of the electriccomponents 116, 118 are pressed by the pressing rubber 122.

Before the electric components 116, 118 are pressed by the compressionbonding device 101, the electric components 116, 118 and the substrate111 are aligned; and terminals of the electric components 116, 118 aredirectly above terminals of the substrate 111 with an adhesive 115inserted therebetween.

The surface of the pedestal 126 is nearly horizontal, and the substrate111 is horizontally placed on that surface. When the pressing head 120is vertically moved downward to press the electric components 116, 118,the terminals of the electric components 116, 118 and the terminals ofthe substrate 111 come into contact with each other, therebyelectrically connecting the electric components 116, 118 and thesubstrate 111 (FIG. 18( b)), because the electric components 116, 118thrust the adhesive 115 aside and move toward the terminals of thesubstrate 111. Thus, the conventional compression bonding device 101 cansimultaneously connect electric components having different thicknessesto one substrate.

However, if the pressing rubber 122 is depressed when it pressescomponents 116, 118, the pressing rubber 122 has the property of bulgingaround the depressed part. Therefore, the bulging part of the pressingrubber 122 climbs over the frame of the head body 121 with the resultthat the surface of the pressing rubber 122 extends horizontally outward(FIG. 18( b)).

FIG. 19 is a plan view showing the manner in which the surface of thepressing rubber 122 extends horizontally outward, i.e., the pressingrubber 122 radially flows around the center C of its planar shape. Dueto the greater amount of movement at the periphery of the pressingrubber 122 as compared with the vicinity of the center C, the electriccomponents 116, 118 pressed by the periphery of the pressing rubber 122horizontally move as the pressing rubber 122 extends, whereby theterminals of the electric components 116, 118 are misaligned from thelocation directly above the terminals of the substrate 111.

If the electric components 116, 118 are misaligned, the terminals of theelectric components 116, 118 fail to come into contact with theterminals of the substrate 111, resulting in the deterioration of areliable connection between the electric components 116, 118 and thesubstrate 111. See, Patent Documents No. JP A 2002-359264 and JP A2005-32952.

SUMMARY OF THE INVENTION

The present invention is made to address the problems described above,and its purpose is to provide a compression bonding device capable ofreliably connecting electric components to a substrate.

In order to address the problems described above, according to oneaspect of the present invention there is provided a compression bondingdevice comprising a pedestal, a dam member and a pressing head. Thepressing head and the pedestal are movable relative to one another topress an object placed on a mounting face of the pedestal with thepressing head. The pressing head comprises ahead body and a pressingrubber which is placed in the head body, and the dam member extendsbeyond the surface level of the pressing rubber and is placed around thepressing rubber, and wherein the pressing rubber, by deforming, pressesthe object placed on the pedestal when the pressing head and thepedestal are moved relative to one another.

According to some aspects, the present invention provides thecompression bonding device wherein the pedestal is inserted into a spacesurrounded by the dam member.

According to one aspect, the present invention provides the compressionbonding device wherein the dam member is separable from the head body.

According to yet another aspect of the present invention, there isprovided a compression bonding device comprising a pedestal and apressing head. The pressing head and the pedestal are movable relativeto one another to press an object to be pressed placed on a mountingface of the pedestal with the pressing head. The pressing head comprisesa head body and a pressing rubber which is placed in the head body, andthe mounting face is surrounded by a dam member having a surface levelthat extends beyond the mounting face.

According to another aspect, the present invention provides thecompression bonding device wherein the pressing head is inserted into aspace surrounded by the dam member.

According to yet another aspect, the present invention provides thecompression bonding device wherein the dam member is separable from thepedestal.

According to a further aspect, the present invention provides thecompression bonding device wherein a compressively deformablecompression member is placed between the pressing rubber and the headbody, and at least when the compression member is compressed, the dammember becomes higher than the surface level of the pressing rubber.

According to another aspect of the present invention there is provided acomponent packaging process comprising placing, on a mounting face of apedestal, an object including a substrate and a plurality of componentshaving different heights on the substrate and pressing the componentswith a pressing rubber provided on a pressing head and fixing thecomponents to the substrate. The object is surrounded by a dam memberand the lateral flow of the pressing rubber due to deformation of thepressing rubber is stopped by the dam member when the pressing rubberpresses the components.

In another aspect, the present invention provides the packaging processcomprising placing an anisotropic conductive film between the componentsand the substrate to bond the components to the substrate, and thenpressing the components with the pressing rubber while heating thesubstrate.

In another aspect, the present invention provides the packaging processcomprising placing a protective film that is releasable from theanisotropic conductive film between the pressing rubber and the objectto be pressed when the components are pressed.

When the pressing rubber is pressed against the object to be pressed,the electric components are less likely to be misaligned even at theperiphery of the pressing rubber because the pressing rubber isprevented from lateral extension by the dam member. As a result of theabsence of lateral extension of the pressing rubber, nearly the totalforce for deforming the pressing rubber converts into a force forpressing the object to be pressed, thereby avoiding wasted pressureduring pressing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional diagram for illustrating a compression bondingdevice according to a first embodiment;

FIG. 2 is a plan view for illustrating the geometry of the pressing headand the pedestal;

FIGS. 3( a)-(c) are sectional diagrams for illustrating a process forpackaging electric components on a substrate;

FIGS. 4( a)-(c) are sectional diagrams for illustrating a process forpackaging electric components using a compression bonding deviceaccording to a second embodiment;

FIG. 5 is a sectional diagram for illustrating another embodiment of thepressing head;

FIG. 6 is a sectional diagram for illustrating a compression bondingdevice according to a third embodiment;

FIG. 7 is a plan view for illustrating the geometry of the pressing headand the pedestal;

FIGS. 8( a)-(c) are sectional diagrams for illustrating a process forpackaging electric components on a substrate;

FIG. 9 is a sectional diagram for illustrating another embodiment of thepressing head;

FIGS. 10( a)-(c) are sectional diagrams for illustrating a process forpackaging electric components on a substrate using a compression bondingdevice according to a fourth embodiment;

FIG. 11 is a plan view for illustrating an embodiment of a dam member;

FIG. 12 is a plan view for illustrating another embodiment of a dammember;

FIGS. 13( a)-(c) are sectional diagrams for illustrating a process forpackaging electric components on a substrate using a compression bondingdevice according to a fifth embodiment;

FIG. 14 is a sectional diagram for illustrating another embodiment of amethod for placing a protective film;

FIG. 15 is a side view for illustrating another embodiment of a dammember;

FIG. 16 is a sectional diagram for illustrating another embodiment of apressing head having a separable dam member;

FIG. 17 is a sectional diagram for illustrating another embodiment of apressing head having a separable dam member;

FIGS. 18( a) and (b) are sectional diagrams for illustrating aconventional packaging process; and

FIG. 19 is a plan view for illustrating extension of a pressing rubber.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference numeral 1 in FIG. 1 represents a first embodiment of acompression bonding device of the present invention. This compressionbonding device 1 has a platform 9, a drive unit 25, a pressing head 20and a pedestal 26. The pressing head 20 has a head body 21, a dam member24 and a bonding part 22.

In this embodiment, the head body 21 is in the shape of a plate and isformed of metal such that head body 21 does not deform when head body 21presses the object to be pressed 10, described later. The bonding part22 is formed of an internally homogeneous elastic material (e.g.,rubber); and, in contrast to metal materials such as iron, the bondingpart 22 deforms when a force is applied thereto, and returns to theoriginal shape when the force is removed.

The bonding part 22 is fixed on the surface of the head body 21. Thepressing head 20 is placed above the platform 9 with the bonding part 22facing downward.

The pressing head 20 is connected to the drive unit 25, so that when thedrive unit 25 is activated, the pressing head 20 moves vertically upwardand downward above the platform 9 with the exposed face of the bondingpart 22 facing downward.

The head body 21 has a quadrangular shape in plan view, and the bondingpart 22 is in the form of a quadratic prism. The size of the head body21 is larger than that of the bonding part 22. A cylindrical dam member24 is placed on the head body 21 externally extending over the bondingpart 22 so as to surround the bonding part 22.

The dam member 24 is made from the same metal as that of the head body21, and the dam member 24 is fixed to the head body 21. The edge of thedam member 24 projects from the surface of the bonding part 22, and aconcave portion 29 is formed, which has the inside face of the dammember 24 as a side face and the surface of the bonding part 22 as abottom face.

The inside face of the dam member 24 is nearly perpendicular to ahorizontal plane, and the surface of the bonding part 22 is nearlyhorizontal. The height of the edge of the dam member 24 from the surfaceof the bonding part 22 is uniform. Thus, an opening 23 formed by theedges of the dam member 24 lies in a horizontal plane and has the samequadrangular shape as that of the bottom face of the concave portion 29.The pedestal 26 is in the form of a quadratic prism and is placedupright on the platform 9 with one base end surface being in closecontact with the surface of the platform 9.

The other base end surface of the pedestal 26 is a mounting face 27 onwhich the object to be pressed 10, described later, is to be mounted.The mounting face 27 is parallel with the surface of the platform 9, sothat the mounting face 27 is nearly horizontal. The mounting face 27 hasthe same shape as that of the opening 23 of the concave portion 29 or asimilar shape slightly smaller than the opening 23 of the concaveportion 29 (FIG. 2) so that the part of the pedestal 26 on which themounting face 27 lies can be inserted into the concave portion 29.

Next, a process for connecting electric components such as asemiconductor element to a substrate using this compression bondingdevice 1 is explained. Reference numeral 10 in FIG. 3( a) represents anobject to be pressed. The object to be pressed 10 has a substrate 11, ananisotropic conductive film 15, and electric components 16, 18.

The anisotropic conductive film 15 is placed on terminals 12 of thesubstrate 11. The electric components 16, 18 are placed on the side ofthe anisotropic conductive film 15 opposite to the substrate 11. Theelectric components 16, 18 have terminals 17, 19 such as bumps or lands.The terminals 17, 19 of the electric components 16, 18 are placed abovethe terminals 12 of the substrate 11.

The electric components 16, 18 are individually mounted on theanisotropic conductive film 15 by a mounting head, not shown, and thenpressed by a small pressure with the mounting head while they arepreliminarily heated at a relatively low temperature. Electriccomponents 16, 18 are tentatively bonded to the substrate 11 by anadhesive force developed by the anisotropic conductive film 15(tentative compression bonding). However, the adhesive force duringtentative bonding is so weak that the electric components 16, 18 readilyfall off the substrate 11. The terminals 12 of the substrate 11 and theterminals 17, 19 of the electric components 16, 18 are in neitherphysical nor mechanical contact with each other, and the anisotropicconductive film 15 exists between them.

The surface of the substrate 11 on which the electric components 16, 18are not placed is flat so that the object to be pressed 10 can bemounted on the pedestal 26 with the flat surface being in close contactwith the mounting face 27.

The anisotropic conductive film 15 is larger than the electriccomponents 16, 18 and partially extends over the electric components 16,18 so that the anisotropic conductive film 15 is exposed between theelectric components 16 and 18. Even if the anisotropic conductive film15 is not exposed between the electric components 16, 18, theanisotropic conductive film 15 partially extends over the outerperipheries of the electric components 16, 18 when it is pressed duringthe pressing step, described later.

The bonding part 22 has a surface formed of a material that can bebonded to the anisotropic conductive film 15, and therefore, aprotective film 5 having low adhesiveness to the anisotropic conductivefilm 15 is placed on the surface of the object to be pressed 10 so as toprevent the bonding part 22 and the anisotropic conductive film 15 fromcontacting each other during the pressing step, described later (FIG. 3(a)).

Here, the mounting face 27 is smaller than the opening 23 and theprotective film 5 is larger than the mounting face 27 so that the outerperiphery of the pedestal 26 including the protective film 5 hangingalong the side face of the pedestal 26 at the edge approximately equalsto the size of the opening 23.

Thus, when the pressing head 20 and the pedestal 26 are aligned so thatthe opening 23 conforms to the outer periphery of the pedestal 26including the protective film 5, and when the pressing head 20 islowered by the drive unit 25, the pedestal 26 is inserted into theconcave portion 29 together with the protective film 5.

The protective film 5 is formed of a compressively deformable material.The pedestal 26 can be inserted into the concave portion 29 even if theouter shape of the pedestal 26, including the protective film 5, isslightly larger than the opening 23.

The electric components 16, 18 can be, for example, semiconductorelements or resistance components, and can have different thicknessesdepending on the type of the component. The thickness difference betweenthe electric components 16 and 18 forms a step on the surface of thesubstrate 11.

FIG. 3( b) shows a state in which the bonding part 22 is in contact withthe thickest electric component 16 on the substrate 11 via theprotective film 5 before the mounting face 27 of the pedestal 26 isinserted into the concave portion 29 together with the object to bepressed 10. The bonding part 22 presses the electric components 16, 18of the object to be pressed 10. In this state, the mounting face 27 liesabove the opening 23 and the edge portion of the side face of thepedestal 26 on the side of the mounting face 27 is inserted into theconcave portion 29 and surrounded by the inside face of the dam member24.

When the pressing head 20 is further lowered from this state and thebonding part 22 is brought relatively close to the substrate 11, thepart of the bonding part 22 in contact with the electric component 16 ispressed and deformed.

The side face of the bonding part 22 is not fixed to the dam member 24,and the bonding part 22 is depressed in not only central but alsoperipheral regions. When the pressing head 20 is further lowered, andpresses the electric components 16, 18, electric components 16, 18 aresuccessively contacted with and pressed by the surface of the bondingpart 22 in the order of thickness from the thicker electric component 16to thinner electric component 18.

When the bonding part 22 is depressed upon contact with the electriccomponents 16, 18, the other regions of the bonding part not contactingthe electric components 16, 18 bulge by the rebound. However, thebonding part 22 does not bulge horizontally outward. Instead, thesurface of the bonding part 22 that does not face the electriccomponents 16, 18 bulges downward because the bonding part 22 is fixedto the head body 21 at the bottom face and surrounded by the dam member24 at the side face. Thus, the surface of the bonding part 22 bulgesdownward at regions between the electric components 16, 18 and aroundthe object to be pressed 10 (FIG. 3( c)).

As noted above, the anisotropic conductive film 15 may be exposedbetween the electric components 16 and 18 or the anisotropic conductivefilm 15 may partially extend over the outer peripheries of the electriccomponents 16, 18 when the electric components 16, 18 are pressed.However, the bonding part 22 does not directly come into contact withthe anisotropic conductive film 15 because the spaces between theelectric components 16, 18 and the electric components 16, 18 themselvesare covered with the protective film 5.

The clearance between the pedestal 26 and the dam member 24 is so smallthat the bonding part 22 does not flow out from the clearance even ifthe surface of it bulges downward around the object to be pressed 10.That is, the downward bulging regions of the bonding part 22 may befilled in the cavities between the electric components 16 and 18, butthe bonding part 22 does not radially flow outward in contrast toconventional methods. Thus, no outward force is exerted on the electriccomponents 16, 18 and the electric components 16, 18 are not misaligned.

The pedestal 26 has a heater 8. The object to be pressed 10 is heated ata predetermined temperature by applying a current to the heater 8. Theflowability of the anisotropic conductive film 15 is increased byheating.

Thus, when the electric components 16, 18 are pressed, the anisotropicconductive film 15 is thrust aside by the electric components 16, 18,and the terminals 17, 19 of the electric components 16, 18 are pressedagainst the terminals 12 of the substrate 11 with electricallyconductive particles in the anisotropic conductive film 15 therebetween.As a result, the electric components 16, 18 and the substrate 11 areelectrically connected to each other.

If the anisotropic conductive film 15 contains a thermosetting resin,the anisotropic conductive film 15 can be cured by heating. If theanisotropic conductive film 15 contains a thermoplastic resin, theanisotropic conductive film 15 can become solidified when thetemperature drops after completion of heating. Thus, the electriccomponents 16, 18 also are mechanically connected to the substrate 11via the cured or solidified anisotropic conductive film 15, therebyproducing an electric device 10 a in which the electric components 16,18 have been mechanically and electrically connected to the substrate11.

The electric device 10 a has higher reliable connection because none ofthe electric components 16, 18 are misaligned when the electriccomponents 16, 18 are pressed.

As described above, the bonding part 22 is not bonded to the anisotropicconductive film 15 because the bonding part 22 does not come intocontact with the anisotropic conductive film 15 when it presses theelectric components 16, 18. Therefore, once the pressing head 20 israised, the surface of the bonding part 22 is easily separated from theelectric device 10 a, and the electric device 10 a is left on thepedestal 26.

When the bonding part 22 is separated from the electric device 10 a, theforce applied to the bonding part 22 is removed and the bonding part 22returns to the original shape that it had before the bonding part 22pressed the electric components 16, 18.

If the electric device 10 a left on the pedestal 26 is removed and a newobject to be pressed 10 is mounted on the pedestal 26, electriccomponents 16, 18 can be continuously connected by the process shown inFIG. 3( a)-(c) and described above.

The height of the edge of the dam member 24 is not specifically limited,but the amount by which the bonding part 22 bulges downward when itpresses the object to be pressed 10 does not exceed the maximumthickness of the object to be pressed 10. Therefore, the bonding part 22does not bulge out from under the dam member 24 if the height from thesurface of the bonding part 22 to the edge of the dam member 24 beforethe bonding part 22 is pressed is equal to or greater than the total ofthe thickness of the thickest electric component 16 (e.g., semiconductorelement) plus the thickness of the substrate 11.

The foregoing description relates to cases in which the concave portion29 has been preliminarily formed in the pressing head 20, the object tobe pressed 10 is inserted in the concave portion 29, and the bondingpart 22 is then contacted with the object to be pressed 10. However, thepresent invention is not limited to such cases.

Reference numeral 3 in FIG. 4( a) represents a compression bondingdevice according to a second embodiment. The compression bonding device3 has the same structure as that of the compression bonding device 1according to the first embodiment. The layout of the pressing head 30and the pedestal 26 also is the same as that of the compression bondingdevice 1 according to the first embodiment except that the bonding part34 of the pressing head 30 is changed as follows.

In contrast to the bonding part 22 of the compression bonding device 1according to the first embodiment, which is formed of rubber, thebonding part 34 of the compression bonding device 3 has a movable plate33, a compression member 31, and a pressing rubber 32 formed of the samerubber as that of the bonding part 22 of the compression bonding device1 according to the first embodiment. The compression member 31 is formedof a material having internal cavities that are collapsed under pressureto decrease the volume, such as sponge-like rubber.

The upper end of the compression member 31 is fixed to the surface ofthe head body 21, the surface of the movable plate 33 is fitted to thelower end of the compression member 31, and the upper end of thepressing rubber 32 is fitted to the back face of the movable plate 33.Thus, the compression member 31, movable plate 33 and pressing rubber 32are arranged in the order as described from the head body 21 toward adownward vertical direction where the pedestal 26 lies.

The compression member 31 has the same columnar shape in horizontalsection as the sectional shape of a region surrounded by the dam member24. Thus, the side face of the compression member 31 is in contact withthe inside face of the dam member 24, but is not fixed to the dam member24. The pressing rubber 32 and movable plate 33 also are unfixed to thedam member 24, and are movable within the region surrounded by the dammember 24.

FIG. 4( b) shows a state in which the pressing head 30 is furtherlowered after the pressing rubber 32 has been contacted with theprotective film 5 on the object to be pressed 10.

The force required to deform the compression member 31 is smaller thanthe force required to deform the pressing rubber 32. When the pressinghead 30 is lowered, the compression member 31 is pressed against thehead body 21 by the pressing rubber 32 and the compression member 31 iscompressed and reduced in thickness before the pressing rubber 32deforms. The compression member 31 is pressed by the pressing rubber 32,whereby a concave portion, which does not exist before compressionmember 31 is compressed by the pressing head 30, is formed.

The compression of the compression member 31 stops when the compressingmember 31 deforms to some extent due to the limitation of the amount bywhich the compression member 31 can deform. If the pressing head 30 islowered further, the pressing rubber 32 deforms (FIG. 4( c)).

When the pressing rubber 32 deforms, the concave portion described aboveis formed, and the edge of the dam member 24 projects below the surfaceof the pressing rubber 32. A clearance between the edge and the pedestal26 is small. Thus, the pressing rubber 32 does not flow out from theclearance and the electric components 16, 18 are not misaligned in thesame manner as with the compression bonding device 1 according to thefirst example.

The configuration of the compression member 31 is not specificallylimited so long as the configuration of the compression member 31 allowsthe compression member 31 to decrease in volume by pressing. Thepressing head represented by reference numeral 35 in FIG. 5 has the samestructure as that of the pressing head 3 shown in FIG. 4( a)-(c) exceptthat the compression member differs, as discussed below. The samemembers in pressing head 35 are explained with the same referencenumbers of pressing head 3.

The compression member of this pressing head 35 is comprised of a spring36. The spring 36 may be compressed by pressing to raise the surface ofbonding part 34, whereby the edge of the dam member 24 may project belowthe bonding part 34.

If the force applied to the pressing rubber 32 can be transferred to thecompression member 36, there is no special need for providing thesupporting plate 33.

The foregoing description relates to cases in which a dam member isprovided on the pressing head 20, but the present invention is notlimited to such cases.

Reference numeral 4 in FIG. 6 represents a compression bonding deviceaccording to a third embodiment. Compression bonding device 4 has thesame structure as that of the compression bonding device 1 according tothe first embodiment, except that a dam member is not provided on thepressing head 40. The dam member 49 is provided around the mounting faceof the pedestal 46, as discussed below.

Here, the bonding part 42 has a pressing rubber that is fitted to thesurface of the head body 41 in the same manner as in the compressionbonding device 1 according to the first embodiment. However, the bondingpart 42 is surrounded by a sliding plate 44 formed of a thin plateinstead of a dam member.

The pedestal 46 is columnar in the same manner as in the compressionbonding device 1 according to the first embodiment The dam member 49 isfixed to the pedestal 46 around the mounting face 47 so as to surroundthe mounting face 47.

The edge of the dam member 49 projects above the mounting face 47 toform a concave portion 45 having the inside face of the dam member 49 asa side face, and the mounting face 47 as a bottom face.

FIG. 7 is a schematic plan view for comparing the planar shape of thepedestal 46 and the planar shape of the pressing head 40. The outerperiphery including the sliding plate 44 of the bonding part 42 is equalto or smaller than the opening 48 of the concave portion 45.

The side face of the bonding part 42 is directed vertically downward andthe side face of the sliding plate 44 is also directed verticallydownward because the thickness of the sliding plate 44 is uniform. Theinside face of the dam member 49 is directed vertically downward,whereby the lower end of the pressing head 40 can be inserted into theconcave portion 45.

Next, a process for connecting the object to be pressed 10 describedabove by using this compression bonding device 4 is explained. In thesame manner as with the compression bonding device 1 according to thefirst embodiment, the object to be pressed 10 is placed on the mountingface 47. The protective film 5 is placed on the opening 48 of the dammember 49, the protective film 5 is pushed into the dam member 49, andthe object to be pressed 10 is covered with the protective film 5 (FIG.8( a)).

The opening 48 of the concave portion 45 is larger than the outerperiphery of the planar shape of the pressing head 40. The protectivefilm 5 is large enough to cover the side face and the periphery of theconcave portion 45 by its edge so that the size of the opening 48 of theconcave portion 45 narrowed by covering opening 48 with the protectivefilm 5 approximately equals the size of the outer periphery of theplanar shape of the pressing head 40.

Thus, when the pressing head 40 and the pedestal 46 are aligned so as toconform the opening 48 to the outer periphery of the pressing head 40,and the pressing head 40 is lowered by the drive unit 25, the lower endof the pressing head 40 is inserted into the opening 48 and surroundedby the dam member 49.

FIG. 8( b) shows a state in which the lower end of the pressing head 40is inserted into the opening 48 and the surface of the bonding part 42is in contact with the thickest electric component 16 via the protectivefilm 5. In this state, the bonding part 42 is not pressed and notdeformed.

In this state, the side face of the bonding part 42 is surrounded by thedam member 49 from the surface of bonding part 42 to the bottom face ifthe sliding plate 44 is flexible, or at least the periphery of thesurface of the bonding part 42 is surrounded by the dam member 49 if thesliding plate 44 is not flexible.

Thus, the side face of the bonding part 42 is surrounded by a rigidmember in either case. When the pressing head 40 is lowered and pressesthe bonding part 42 against the object to be pressed 10, the bondingpart 42 does not bulge horizontally outward. Instead, its surface bulgesdownward (FIG. 8( c)).

The distance from the edge of the surface of the bonding part 42 to thedam member 49 is short because the sliding plate 44 is thin and theclearance between the pressing head 40 and the dam member 49 also ismall. Even if the bonding part 42 is raised and extends outward, thebonding part 42 is stopped by the dam member 49 and therefore, theamount of extension is small and the electric components 16, 18 are lesslikely to be misaligned.

If there is a great difference between the size of the planar shape ofthe pressing head 40 and the size of the opening 48 of the dam member49, the clearance between the dam member 49 and the side face of thepressing head 40 may be filled with the protective film 5 by designingthe protective film 5 as thick as possible.

The foregoing description relates to cases in which the bonding part 42is surrounded by the sliding plate 44, but the present invention is notlimited to such cases. For example, the side face of the bonding part 42may be exposed without providing the sliding plate 44 around it, asshown in FIG. 9.

The foregoing description relates to cases in which the dam member isfixed to the head body 41 or pedestal 46, but the present invention isnot limited to such cases, and the dam member may be formed of a memberthat is separate from the pedestal or the head body, and the dam membermay be in close contact with the pedestal or the head body when theobject to be pressed 10 is pressed.

Reference numeral 7 in FIG. 10( a) represents a compression bondingdevice according to a fourth embodiment. The compression bonding device7 has the same structure as that of the compression bonding device 1according to the first embodiment, and the layout of the pressing head70 and the pedestal 26 also is similar except that the dam member 74 ofthe pressing head 70 is formed of a member that is separate from thehead body 71. FIG. 10( a) shows that a state in which the dam member 74is separated from the head body 71.

The dam member 74 has a plurality of plate-shaped unit members 75, asshown in FIG. 11. The unit members 75 arranged along the side face ofthe bonding part 72 have their surfaces oriented to be in close contactwith the head body 71 by a moving means, not shown. In the state whereeach unit member 75 is in close contact with the head body 71, the sideface of the bonding part 72 is surrounded by the unit members 75.

FIG. 10( b) shows a state in which the bonding part 72 is in contactwith the protective film 5 on the thickest electric component 16, andthe bonding part 72 is not pressed and not deformed. The unit members 75should be brought into close contact with the head body in this state.The side face of the bonding part 72 may be surrounded by the unitmembers 75 when the bonding part 72 is pressed and deformed.

When the bonding part 72 is a pressing rubber, each unit member 75should be fitted to project at the lower end from the surface of thebonding part 72 before the bonding part 72 is pressed so that thebonding part 72 may not bulge out from under the dam member 74 even ifthe pressing head 70 is further lowered to press the bonding part 72 inthe same manner as with the compression bonding device 1 according tothe first embodiment, so that the electric components 16, 18 are notmisaligned (FIG. 10( c)).

The bonding part 72 may also be formed of a pressing rubber and acompression member.

Reference numerals 90 and 95 in FIGS. 16 and 17 represent pressing headsin which a dam member 74 can be separated from a head body 71 and abonding part 72 has compression members 31, 36 and a pressing rubber 32.The pressing head 90 in FIG. 16 has the same structure as that of thebonding part 34 of the pressing head 30 in FIG. 4( a)-(c), and thepressing head 95 in FIG. 17 has the same structure as that of thebonding part 34 of the pressing head 35 in FIG. 5. Moreover, the layoutof the head body 71 and the unit member 75 is similar to that of thepressing head 70 in FIG. 10 and will be explained with the samereference numerals for the same members.

The pressing heads 90, 95 can also be designed in such a manner that,when the dam member 74 is fitted to the head body 71, the edge of thedam member 74 may be flush with the surface of the bonding part 34before the bonding part 34 is pressed. Alternatively, the surface of thebonding part 34, before the bonding part 34 is pressed, may projectbelow the edge of the dam member 74, or the edge of the dam member 74may project below the surface of the bonding part 34 before the bondingpart 34 is pressed so long as a concave portion having the surface ofthe pressing rubber 32 as a bottom face is subsequently formed bycompression of the compression member 31.

The foregoing description relates to cases in which the dam member 74 isformed of a plurality of unit members 75, but the present invention isnot limited to such cases. For example, the dam member 78 may beinitially cylindrically shaped as shown in FIG. 12. In this case, thepressing head 70 is inserted into the cylinder of the dam member 78 andthe bonding part 72 is surrounded by the inner periphery surface of thedam member 78 before the object to be pressed 10 is pressed and thebonding part 72 is deformed. In this case, misalignment of the electriccomponents 16, 18 can be prevented because lateral extension of thebonding part 72 is stopped by the dam member 78.

Next, cases in which the dam member can be separated from the pedestalare explained.

Reference numeral 8 in FIG. 13( a) represents a compression bondingdevice according to a fifth embodiment of the present invention. Thecompression bonding device 8 has the same structure as that of thecompression bonding device 4 according to the third embodiment describedabove. The layout of the pedestal 86 and the pressing head 40 also issimilar except that the dam member 89 is another member that can beseparated from the pedestal 86. FIG. 13( a) shows a state in which thedam member 89 is separated from the pedestal 86.

The dam member 89 may be formed of a plurality of unit members as shownin FIG. 11 or may be formed of a single cylinder as shown in FIG. 12.When the dam member 89 is formed of a plurality of unit members, eachunit member is arranged along the edge of the mounting face 87 and is inclose contact with the mounting face 87 so as to surround the mountingface 87. When the dam member 89 is cylindrical, the pedestal 86 isinserted into the lower end of the cylinder, thereby bringing the dammember 89 into close contact with the pedestal 86.

In the state where the dam member 89 is in close contact with thepedestal 86, the edge of the dam member 89 projects above the mountingface 87, whereby a concave portion 85 is formed, which has the innerperipheral surface of the dam member 89 as a side face and the mountingface 87 as a bottom face.

The magnitude relation between the opening of the concave portion 85 andthe pressing head 40 is similar to that of the compression bondingdevice 4 shown in FIGS. 6 and 7 so that the lower end of the pressinghead 40 can be inserted into the concave portion 85.

FIG. 13( b) shows a state in which the bonding part 42 is in contactwith the thickest electric component 16 of the object to be pressed 10on the mounting face 87 via the protective film 5. In this state, thebonding part 42 is not pressed and not deformed. At this state, the dammember 89 should be brought into close contact with the pedestal 86, tothereby surround the mounting face 87 by the dam member 89.

In the compression bonding device 8, horizontal extension of the bondingpart 42 also becomes small and prevents misalignment of the electriccomponents 16, 18 because the raised surface of the bonding part 42 isstopped by the dam member 89 (FIG. 13( c)).

If the planar shape of the protective film 5 is so large that it extendsover the mounting face 87, the protective film 5 is not entangledbetween the dam member 89 and the pedestal 86 by fitting the dam member89 to the pedestal 86 and then applying the protective film 5 thereon.

As shown in FIG. 14, the protective film 5 may be wound around thepressing head 40 rather than being applied on the mounting face 87.Further, the pressing head 40 may be pressed against the object to bepressed 10 while the surface of the bonding part 42 is covered.

The foregoing description relates to cases in which the bonding part 22is entirely surrounded by the dam member 24 of the pressing head 20 orthe dam member 49 when the object to be pressed 10 is pressed, but thepresent invention is not limited to such cases. For example, one or moreslits 99 may be formed in the dam member 24, and the side face of thebonding part 22 may be partially exposed, as shown in FIG. 15, so thathorizontal extension of the bonding part 22 can be prevented when theobject to be pressed 10 is pressed.

The shape and size of the protective film 5 are not specificallylimited. A protective film 5 having a size that does not extend over themounting faces 27, 47, 87 may be used, or a protective film 5 coveringonly a partial surface of the object to be pressed 10 may be used, aslong as any contact can be avoided between the anisotropic conductivefilm 15 and the bonding parts 22, 34, 42, 72.

If the adhesiveness between the anisotropic conductive film 15 and thebonding parts 22, 34, 42, 72 is low, the bonding parts 22, 34, 42, 72may be brought into direct contact with the object to be pressed 10without using the protective film 5. As a method for decreasing theadhesiveness between the bonding parts 22, 34, 42, 72 and theanisotropic conductive film 15, the material from which the pressingrubber is formed may be changed to one having low adhesiveness to theanisotropic conductive film 15, or a release layer having releasabilityagainst the anisotropic conductive film 15 may be provided on thesurface of the pressing rubber.

In this manner, the compression bonding devices of the presentapplication can connect electric components to a substrate without usinga protective film 5. However, if there is a large clearance between thedam member and the pressing head or between the dam member and thepedestal, the clearance can be decreased by covering the side face ofthe dam member with a protective film 5.

Thus, the pedestal, dam member and pressing head can be manufactured atlow costs without using a mold or the like, and even if the moldingprecision is low, the clearance between the dam member and the pressinghead or between the dam member and the pedestal can be filled byappropriately selecting the thickness of the protective film 5.

The type of the substrate 11 used in the present invention is notspecifically limited, and various substrates such as rigid substratesand flexible substrate can be used.

The type of the electric component to be connected to the substrate 11is not specifically limited. Furthermore, the compression bondingdevices and connecting processes of the present application can be usedto connect not only electric components but also another substrate ontothe substrate 11.

The anisotropic conductive film 15 may contain either one or both of athermoplastic resin and a thermosetting resin.

The types of the thermosetting resin and thermoplastic resin are notspecifically limited. For instance, one or more thermosetting resinssuch as epoxy resins, acrylic resins and urethane resins can be used,and one or more thermoplastic resins such as phenoxy resins andpolyvinyl alcohols can be used.

The type of conductive particles is not specifically limited. Forinstance, not only metal particles but also resin particles coated witha metal layer can be used.

Instead of using the anisotropic conductive film 15, a pasty anisotropicconductive adhesive may be applied on the surface of the substrate 11and electric components may be bonded to the anisotropic conductiveadhesive, thereby obtaining an object to be pressed 10.

The type of the protective film is not specifically limited, butpreferably has releasability against the anisotropic conductive film 15described above, e.g., a molded film of polytetrafluoroethylene or amolded film of silicone rubber.

The elastic material forming the pressing rubber is not specificallylimited, and elastomers having rubber hardnesses (according to JIS S6050) of 40, 80 could be used by way of example.

Rubber hardness is determined by the method described in “6. Testmethod” in JIS S 6050:2002, as follows.

Samples having stood for 24 hours or more after production are used forthe test. General matters common to chemical analyses are as shown inJIS K 0050. A hardness tester is used in a test for hardness. Thesurface of a test sample piece horizontally held is brought into contactwith the pressurizing face while the intender point of the tester isvertical. Then, the scale is immediately read as a positive number. Asto the measurement point of the test sample piece, the entire surface ofthe test sample piece is divided into three, each center portion ismeasured individually, and then their median values become hardness ofthe test sample piece.

The hardness tester here refers to a spring hardness tester having asemi-circular indenter point of 5.08 mm±0.02 mm in diameter. The heightof the indenter point is 2.54±0.22 mm at scale 0, and 0 mm at scale 100.The relationship between scale and spring force is shown in Table 1below.

TABLE 1 Relationship between scale and spring force Scale 0 10 20 25 3040 50 60 70 75 80 90 100 Spring Force N 0.54 1.32 2.11 2.50 2.89 3.684.46 5.25 6.03 6.42 6.82 7.60 8.39

When elastomers having rubber hardnesses of 40, 60, 80 were measured forrubber hardness every 30° C. in a range of the measurement temperatureof 30° C. to 240° C., the rubber hardness varied within ±2. It can besaid that the rubber hardness is not influenced by temperature changes,because this value is within measurement error.

Elastomers used for the pressing rubber may include both natural andsynthetic rubbers, and preferably silicone rubber in terms of heatresistance and pressure resistance.

The foregoing description relates to cases in which the pressing head 20is moved upward and downward by the driving unit 25, but the presentinvention is not limited to such cases. For example, the platform 9 maybe vertically moved upward and downward while the pressing head 20 isfixed, or both of the pressing head 20 and the platform 9 may bevertically moved upward and downward so far as the pressing head 20 andthe platform 9 are relatively moved.

Embodiments

A semiconductor element 16 and a substrate 11 were connected by usingthe compression bonding device 1 according to the first embodiment withvarying heights from the surface of the bonding part 22 to the edge ofthe dam member 24 before the bonding part 22 is pressed (edge height).The amount of horizontal displacement of the semiconductor element 16was measured.

Here, the distance (clearance) from the side face of the pressing head20 to the inner wall face of the dam member 24 was 50 μm when thepressing head 20 was inserted into the concave portion 29. By using aprotective film 5 having a thickness of 50 μm, a pressure was appliedwith substantially no clearance between the pressing head 20 and the dammember 24. The thickness of the semiconductor element 16 was 0.4 mm, andthe thickness of the substrate 11 was 0.6 mm.

The maximum amount of displacement of the semiconductor element 16measured is shown in Table 2 below along with the edge height of the dammember 24.

TABLE 2 Tab. 2: Edge height of a dam member and maximum amount ofdisplacement Maximum amount of Edge heigh (mm) displacement (mm) −3.00.050 −1.0 0.050 0 0.050 1.0 0.020 2.0 0.015 3.0 0.015

In the column “edge height” in Table 2 above, “0 mm” means that the edgeof the dam member 24 is flush with the surface of the bonding part 22,“+” means that the edge of the dam member 24 projects below the surfaceof the bonding part 22, and “−” means that the surface of the bondingpart 22 projects below the edge of the dam member 24.

As shown in Table 2 above, the maximum amount of displacement becomessmall when the edge of the dam member 24 projects from the surface ofthe bonding part 22 before the bonding part 22 is pressed, while theamount of displacement of the semiconductor element 16 is large when thesurface of the bonding part 22 is flush with the edge of the dam member24 or projects from the edge of the dam member 24.

The above test confirmed that displacement of electric components isprevented and highly reliable electric devices can be fabricated byproviding the dam member 24 in such a manner that its edge projects fromthe surface of the bonding part 22.

1. A compression bonding device comprising: a pedestal; a dam member; apressing head; a protective film; and a heater, the pressing head andthe pedestal being movable relative to one another to press an object tobe pressed placed on a mounting face of the pedestal with the pressinghead, wherein the pressing head has a head body and a pressing rubberwhich is placed in the head body, wherein the protective film is placedon the object placed on the pedestal, wherein the pressing rubber isconfigured to press the object while being in contact with theprotective film, wherein the dam member having a surface level thatextends beyond the pressing rubber is placed around the pressing rubberwhile the object is pressed, and wherein a lateral flow of the pressingrubber due to deformation of the pressing rubber is stopped by the dammember when the object is pressed with the pressing rubber.
 2. Thecompression bonding device according to claim 1, wherein the pedestal isinserted into a space surrounded by the dam member.
 3. The compressionbonding device according to claim 1, wherein the pressing head isinserted into a space surrounded by the dam member.
 4. The compressionbonding device according to claim 1, wherein the dam member is separablefrom the head body.
 5. The compression bonding device according to claim1, wherein a compressively deformable compression member is placedbetween the pressing rubber and the head body, and at least when thecompression member is compressed, the dam member becomes higher than thesurface level of the pressing rubber.